When they teach their subject, economists almost always start with microeconomics. Why? Because it's easier to reach clear-cut answers when you start small. Once you know what you're talking about, you can build on it. When economists can't give their macroeconomics strong microfoundations, they worry. Those who skip straight to macro have a serious risk of ending up with a bunch of half-baked floating abstractions.

This doesn't mean that starting at the macro level invariably leads to half-baked floating abstractions. But there is a solid presumption in favor of "micro first" - and this presumption is hardly specific to economics. The best way to reach clear-cut answers is normally to start small, then build on what you know.

An immediate implication: If a field (a) focuses on the macro level and (b) has been spinning its wheels for centuries, you should consider the possibility that (a) and (b) are connected. Ethics is a case in point. Major ethical theories start big - making sweeping moral claims about all actions for all people. Utilitarianism is the most obvious example. But the same goes for Kant, Rawls, and Rand. And even according to philosophers themselves, the field of ethics hasn't made a lot of progress over the centuries.

My prescription: Ethicists should reallocate most of their effort to microethics. Start with simple cases where right and wrong are obvious. Is it wrong to punish an escaped murderer by torturing his infant child? Is it wrong to welsh on a $20 bet? Is it wrong to steal an alcoholic's liquor? To refuse to give all your surplus income away to needy strangers? Then build from there. Once you've got these conclusions under your belt, you can move on to slightly harder cases - like movies. Last night I saw the surprisingly watchable Assassination Games, and I'm still pondering the ethics.

I'm not saying that microethics would instantly resolve macroethical controversies. (Though perhaps it should). But a decade of microethical research would do more to advance ethics than another century of academics as usual.